Perovskite solar cells with carbon back contact (C-PSC) represent a promising architecture that allows for a simplification of the manufacture process and a stabilization of the cell performances. In this work, we designed a fully printable C-PSC using a homemade mesoporous alumina (Al2O3) ink. By increasing the alumina layer thickness we show that fill factor reduces, short-circuit current increases, while open circuit voltage increases until a thickness of 1.2 mu m. In order to improve performances of PSCs, we investigated a water pre-treatment before perovskite deposition. We show that water pre-treatment improves pore filling, leads to a reduction of charge recombination, and improves the conversion of PbI2 crystals into perovskite. The water pre-treatment permits to obtain an average efficiency increasing of 16% with respect to cells without water pre-treatment.